Sports enthusiasts such as skiers, surfers and bikers often prefer delaying their changing into appropriate sporting attire until their arrival at their particular sporting venue. Changing into appropriate footware such as biking shoes and skiing boots is especially difficult without a seat. Often the sports enthusiast tows sports equipment such as a boat on a trailer or a collapsible tent trailer. In launching the boat, having one or more seats adapted to be deployed as standing platforms during the launch keeps the person out of the water and out of the way of the towing vehicle during the launch phase. Accordingly, it is desirable to have a utility seat that attaches to a receiver hitch via an adaptor that is detachably engaged via a tow ball of the ball plate assembly.